1. Field of the Invention
The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus capable of forming high-gloss images efficiently.
2. Description of the Related Art
Conventional image forming apparatuses, such as printers, facsimiles, copiers, and multifunction apparatuses that print, fax, copy, and so on, generally use an electrophotographic process for image forming. In the electrophotographic process, toner is used to form images.
Further, such image forming apparatuses generally employ a fixing unit to fix the toner image formed on a recording medium by applying heat and pressure thereto at a nip formed between a heat roller and a pressure roller, as the recording medium bearing the toner image passes between the heat roller and the pressure roller.
In such a fixing unit, if resin included in the toner is melted by heat, adheres to the heat roller, and solidifies, surface asperities may be formed on the heat roller. Further, when the toner image is fixed by such a heat roller, small surface asperities may be formed also on the toner image after the fixing process. Accordingly, it is not possible to obtain smooth and high-gloss images.
To obtain such high-gloss images, many attempts have been made. For example, in some approaches, a gloss assist sheet is fed to the fixing unit to overlap an imaging surface of a recording medium so as to smooth the surface of the image after the fixing process (e.g., JP-2008-20520-A, JP-2008-51857-A).
JP-2008-64804-A describes an image forming apparatus which includes a separation unit to separate the gloss assist sheet from the recording medium after the fixing process. The separation unit includes a wedged-shape separation member. The gloss assist sheet is separated from the recording medium by introducing a top edge of the separation member into a space between the recording medium and the gloss assist sheet.
However, according to the image forming apparatus having the separation unit described in JP-2008-64804-A, when the separated gloss assist sheet is used again, it is required that a user load the gloss assist sheet in a sheet material storage unit. Accordingly, when a plurality of high-gloss images are printed successively, the number of times the user loads the gloss assist sheet in the apparatus is increased, thus increasing the time and effort required of the user.
In view of the foregoing, the inventor of the present invention recognizes that there is a need for an image forming apparatus to streamline setting of the gloss assist sheet when the gloss assist sheet is reused.